Refrigerant

ABSTRACT

An object of the present invention is to provide a refrigerant in which an odorant is added, the odorant being compatible with refrigerants and refrigerating device oils, and having no reactivity with refrigerating device oils and materials forming refrigerating circuits, and to provide a refrigerating device in which the refrigerant is circulated in the refrigerating circuit.  
     A refrigerant whose main component is a hydrocarbon having 1 to 4 carbon atoms, or a flammable hydrocarbon fluoride obtained when one or more hydrogen atoms of the hydrocarbon is substituted by fluorine atoms, the refrigerant containing a tetrahydrothiophene as an odorant, and a refrigerating device in which the refrigerant is circulated are provided.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a refrigerant and arefrigerating device, and in particular, to a flammable refrigerant inwhich an odorant is incorporated and a refrigerating device whichutilizes the flammable refrigerant.

[0003] 2. Description of the Related Art

[0004] Refrigerators and refrigerating devices for automatic vendingmachines and showcases have usually used, as a conventional refrigerant,chlorofluorocarbon refrigerants such as dichlorodifluoromethane(CFC-12), or hydrochlorofluorocarbon refrigerants such aschlorodifluoromethane (HCFC-12). When these refrigerants are releasedinto the atmosphere and reach the ozone layer above the earth, theproblem of destruction of the ozone layer arises. Thus, use ofchlorofluorocarbon flon and hydrochlorofluorocarbon flon, which arerefrigerants which have been used until now in refrigerating devices,has been prohibited or restricted.

[0005] As a result, hydrofluorocarbon refrigerants such as CH₂FCF₃(HFC-134a) have been used as a substitute flon of the aboverefrigerants. However, even with such HFC refrigerants, a problem arisesin that the effect thereof on global warming, which is another globalenvironmental issue, is near the same level as that of the conventionalHCFC-22 (CHCIF₂) which is an HCFC refrigerant.

[0006] To solve such problems, hydrocarbon (HC) refrigerants such aspropane and isobutane have recently been used as refrigerants forrefrigerating devices. However, because the HC refrigerants areflammable, there is the possibility of spontaneous ignition or explosionwhen these refrigerants leak from a refrigerating circuit. Particularly,in the case of home refrigerators, since many heat sources oftendisposed near the home refrigerator, leakage of the flammablerefrigerant may cause a major accident.

[0007] In view of the aforementioned facts, for refrigerating deviceswhich utilize flammable gas refrigerants, it has been proposed to addodorants to refrigerants so that the leakage of the gas refrigerants canbe detected. For example, Japanese Patent Application Laid-Open (JP-A)No. 8-14675 discloses addition of methylmercaptan, as an odorant made ofsulfur-containing organic substance, to the HC refrigerant. However,methylmercaptan has high reactivity with copper, which is a materialused in the refrigerating circuit, and changes (corrodes) the coppersurface, which results in a shortened life of the copper. In addition,methylmercaptan also has high reactivity with refrigerating device oils.When it reacts with the refrigerating device oil, an insoluble reactionproduct will be generated in the refrigerant or in the refrigeratingdevice oil, which insoluble reaction product may cause clogging of acapillary tube or the like in the refrigerating circuit after operationfor a long period of time.

[0008] JP-A No. 8-245952 discloses that, in addition to mercaptane(methyl mercaptane, ethylmercaptane), dimethyl sulfide is added, as anodorant, to a flammable HFC refrigerant. However, dimethyl sulfide doesnot have an extremely strong offensive smell (it only has an onion-likesmell), so that dimethyl sulfide alone does not sufficiently function asan odorant for the flammable refrigerant. As a result, it is generallyused in combination with other odorants such as mercaptanes.

[0009] Therefore, a flammable refrigerant incorporating an odorant whichodorant has no reactivity with copper, a material of the refrigeratingcircuit, or refrigerating device oils has not been developed.

[0010] An odorant is generally required to have such characteristicsthat it has an abnormal smell, is stable as a chemical substance, isnon-toxic and harmless to humans, and the like. In addition, particularcharacteristics are required depending on materials to which the odorantis added. Therefore, a substance known as an odorant can not always beused as the odorant for other materials.

[0011] For example, tetrahydrothiophene (THT) has already been used asan odorant in combustion gases such as town gas (“Perfume” No. 146, June1985). In addition to the above characteristics generally required forodorants, the following particular characteristics are necessary forodorants used in combustion gases: it burns safely and is odorless andharmless after combustion takes place, the odor is held in the gas so asnot to be absorbed by gas pipes and meters, and the like. Because addingTHT to combustion gases and adding THT in refrigerants for refrigeratingcircuit have been considered as two different things, use of THT inrefrigerants has not been examined.

SUMMARY OF THE INVENTION

[0012] In view of the aforementioned facts, an object of the presentinvention is to provide a refrigerant in which an odorant is added, theodorant being compatible with refrigerants and refrigerating deviceoils, and having no reactivity with refrigerating device oils andmaterials used for refrigerating circuits, and to provide arefrigerating device in which the refrigerant is circulated in therefrigerating circuit.

[0013] The following refrigerants and refrigerating devices of thepresent invention are provided in order to achieve the above-describedobject.

[0014] A first aspect of the present invention is a refrigerant the maincomponent of which is a hydrocarbon having 1 to 4 carbon atoms, or aflammable hydrocarbon fluoride derived by substituting one or morehydrogen atoms of the hydrocarbon with fluorine atoms, the refrigerantincluding a tetrahydrothiophene as an odorant.

[0015] A second aspect of the present invention is the refrigerant inwhich the amount of the odorant is in the range of 10 wt ppm to 0.5 wt%.

[0016] A third aspect of the present invention is the refrigerant inwhich purity of the hydrocarbon or the flammable hydrocarbon fluoride isat least 99.0 vol %, the content of unsaturated hydrocarbon is no morethan 0.01 wt %, and the entire sulfur content is no more than 0.1 wtppm.

[0017] A fourth aspect of the present invention is a refrigeratingdevice in which the refrigerant of the first aspect of the invention iscirculated in a refrigerating circuit in which a compressor, a heatreleasing device, an expansion mechanism, and an evaporator areincluded.

[0018] A fifth aspect of the present invention is the refrigeratingdevice in which a refrigerating device oil used in the compressor has aviscosity at 40° C. of 5 to 300 cSt.

[0019] A sixth aspect of the present invention is the refrigeratingdevice in which the refrigerating device oil includes a metalinactivating agent.

[0020] A seventh aspect of the present invention is the refrigeratingdevice in which the refrigerating device oil includes one or moreadditives selected from the group consisting of moisture- and/or acidtrapping agents, antioxidants, and extreme pressure additives.

[0021] An eighth aspect of the present invention is the refrigeratingdevice in which residual oxygen in the refrigerating circuit is no morethan 0.1 vol % of an internal capacity of the refrigerating circuit, anda residual moisture content in the refrigerating circuit is no more than500 wt ppm with respect to a total of the refrigerant and therefrigerating device oil.

[0022] A ninth aspect of the present invention is the refrigeratingdevice in which the refrigerating circuit is made of copper or copperalloy.

[0023] A tenth aspect of the present invention is the refrigeratingdevice in which the refrigerating circuit further includes a dryingdevice.

[0024] An eleventh aspect of the present invention is the refrigeratingdevice in which the drying device contains a synthetic zeolite whoseeffective diameter falls in the range of 3 to 6 Å.

BRIEF DESCRIPTION OF THE DRAWING

[0025]FIG. 1 is a schematic view illustrating one example of arefrigerating circuit in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The main component of the refrigerant of the present invention isa hydrocarbon having 1 to 4 carbon atoms, or a flammable hydrocarbonfluoride in which some of the hydrogen atoms of hydrocarbon aresubstituted by fluorine atoms. These refrigerants are known as flammablerefrigerants. Examples of the hydrocarbon having 1 to 4 carbon atomsinclude propane, isobutane, or the like. The flammable hydrocarbonfluoride is the hydrocarbon fluoride in which a part of hydrocarbonhaving 1 to 3 carbon atoms is substituted by fluorine atoms, andexamples thereof include: difluoromethane, difluoroethane (1,1- or1.2-difluoroethane), trifluoroethane (1,1,1- or 1,1,2-trifluoroethane),tetrafluoroethane (1,1,1,2- or 1,1,2,2-tetrafluoroethane),pentafluoroethane, pentafluoropropane (1,1,2,2,3- or 1,1,1,3,3-pentafluoropropane, etc.), hexafluoropropane (1,1,2,2,3,3- or1,1,1,2,3,3-hexafluoropropane, etc.), heptafluoropropane (1,1,1,2,2,3,3-or 1,1,1,2,3,3,3-heptafluoropropane, etc.), or the like. The purity ofthe hydrocarbon is preferably 99.0 vol % or higher, the total amount ofunsaturated hydrocarbon contained therein is preferably 0.01 wt % orless, and the entire sulfur content contained therein is preferably 0.1wt ppm or less. If the purity of the hydrocarbon or the flammablehydrocarbon fluoride is less than 99.0 vol %, there are cases in whichadverse effects due to the impurities may arise. If the total amount ofunsaturated hydrocarbon exceeds 0.01 wt %, unsaturated hydrocarbonreacts with the refrigerating device oil in the refrigerating circuitand with materials forming the refrigerating circuit. As a result,deterioration of the refrigerating circuit tends to occur. Further, ifthe entire content of sulfur exceeds 0.1 wt ppm, the reaction with thecopper forming the pipes will exceed allowable limits, which is notpreferable.

[0027] Next, the odorant used in the present invention will bedescribed. An odorant is generally required to have such characteristicsthat it has an abnormal offensive smell, is stable as a chemicalsubstance, is non-toxic and harmless to humans, and the like. Inaddition to the above characteristics, the following particularcharacteristics are required for the odorant particularly for use inrefrigerants: it does not react with materials, particularly copper,forming the refrigerating circuit; it is compatible with refrigerants;and it is compatible with, but does not react with the refrigeratingdevice oil which is mixed with the refrigerant and together circulatesin the refrigerating circuit. Other than these characteristics, theodorant must have an appropriate boiling point and solidifying point. Ifthe boiling point is too high, the odorant hardly vaporizes and does notfunction well as an odorant. If the solidifying point is too high, theodorant solidifies in the refrigerant, which may cause clogging of therefrigerating circuit.

[0028] The odorant used in the refrigerant of the present invention istetrahydrothiophene (hereinafter, sometimes referred to as THT). THT isa liquid substance at ordinary temperature and has a unique offensivesmell (a smell like that of coal gas), a boiling point of 122° C., and asolidifying point of −96° C. Accordingly, THT sufficiently functions asan odorant in the case of leakage of the refrigerant, and, because THTdoes not solidify when used in refrigerants, problems such as cloggingof the refrigerating circuit can be avoided. In addition, THT has goodcompatibility with above-described hydrocarbon, flammable hydrocarbonfluoride, and later-described refrigerating device oils. As an importantcharacteristics, THT does not react with materials, especially copperand copper alloy, which form the refrigerating circuit. Therefore, THTdoes not cause corrosion of copper pipes, heat exchangers, or the like.In addition, since THT does not react with refrigerating device oils,clogging of the refrigerating circuit due to insoluble reaction productswill not occur even after operation for a long period of time.

[0029] The added amount of the odorant in the refrigerant is preferably10 wt ppm to 0.5 wt %. When less than 10 wt ppm is used, it becomesdifficult to detect leakage of the refrigerant. If even more than 0.5 wt% is added, the odor becomes stronger than necessary, and, as a result,handling of the odorant becomes difficult when the odorant is filled inthe refrigerant circuit and recovered therefrom. Therefore, theaforementioned range is preferable.

[0030] The present invention also relates to a refrigerating devicewhich circulates a refrigerant through a refrigerating circuit in whicha compressor, a heat releasing device, an expansion mechanism, and anevaporator are included.

[0031]FIG. 1 is a schematic view for explaining one example of a coolingcircuit in the refrigerating device of the present invention. In FIG. 1,reference numeral 100 represents a compressor, 120 denotes a heatreleasing device, 140 represents an expansion mechanism (a capillarytube), 160 denotes a gas cooler, 180 is a four-way valve, and 200represents a drying device. The arrows denote the direction in which therefrigerant flows. The solid line arrows illustrate the flow of therefrigerant when the ordinary cooling is carried out, and the dashedarrows indicate the flow of the refrigerant when the defrosting iscarried out. In FIG. 1, an example is illustrated in which the dryingdevice is provided between the expansion mechanism 140 and the heatreleasing device 120. However, the drying device does not have to beprovided at this position, and may be provided at another low-pressureposition.

[0032] For example, in a case in which the interior of a room is to becooled, the refrigerant gas, which is under high temperature and highpressure and is compressed by the compressor 100, passes through thefour-way valve 180, such that heat is released at the heat releasingdevice 120 and the refrigerant is cooled so as to become alow-temperature, high-pressure refrigerant liquid. The pressure of therefrigerant liquid is lowered by the expansion mechanism 140 (e.g., acapillary pipe, a temperature-type expansion valve, or the like), so asto become a low-temperature, low-pressure liquid containing a slightamount of gas. This liquid reaches the gas cooler 160, obtains heat fromthe air within the room, evaporates, passes through the four way valve180, and reaches the compressor 100 to cool the interior of the room.When the gas cooler is to be defrosted, the flow of the refrigerant ischanged to the opposite direction by the four way valve 180, and theopposite operations are carried out so as to defrost. When an exteriorheat changer is used as the heat releasing device while an interior heatexchanger is used as the gas cooler, the present invention can also beapplied to a heating and cooling type air conditioner.

[0033] The refrigerating device oil is a lubricating oil sealed withinthe compressor. A mixture of a refrigerant and a small amount of therefrigerating device oil circulates through the entire refrigeratingcircuit. Therefore, the odorant incorporated in the refrigerant iscaused to be in contact with the refrigerating device oil. Accordingly,the odorant is required to be compatible with, and have no reactivitywith the refrigerating device oil.

[0034] Accordingly, the low-temperature characteristic and themiscibility with respect to the refrigerant, of the refrigerating deviceoil are important for the performance of the cooling system. The mixtureof the refrigerant and the refrigerating device oil must be stable(e.g., must be resistant to hydrolysis) at operating temperatures of therefrigerating device. Further, the mixture must not be harmful to (e.g.,must not corrode or lower the insulation of) the compressor as well asthe other materials used in the refrigerating circuit. Further, aportion of the refrigerating device oil is mixed in with the compressedrefrigerant gas, is circulated together with the refrigerant in therefrigerating circuit of the refrigerating device, and flows into theevaporator through an expansion mechanism such a capillary pipe or anexpansion valve. At the low temperature portions in the refrigeratingcircuit, the refrigerating device oil which moves from the compressorloses its fluidity, and the refrigerating device oil tends to remainthereat. If the refrigerating device oil does not return to thecompressor from the evaporator, the level of the oil on the surfaces inthe compressor will fall, and this may cause heat damage (seizing due toincreased temperature).

[0035] The viscosity of the refrigerating oil at 40° C. is preferably 5to 300 cSt. When the viscosity is greater than 300 cSt, the fluidity isinsufficient, and the fluidity tends to be lost, especially at lowtemperatures. Further, if the viscosity is less than 5 cSt, insufficientoil film strength at the lubricating surfaces and an insufficientsealing effect at the compressor mechanism tend to occur.

[0036] Further, the volume specific resistivity of the refrigeratingdevice oil at the refrigerating device of the present invention ispreferably 10¹⁰ Ω·cm or more.

[0037] General petroleum oils, ether synthetic oils, ester syntheticoils, fluorine synthetic oils and the like can be used as therefrigerating device oil at the refrigerating device of the presentinvention. Examples of petroleum oils are paraffin oils and naphtheneoils. Further, polyvinylethers and polyalkylene glycols may be used asthe ether synthetic oils. Examples of the ester synthetic oils arepolyol ester oil, carbonate ester, and the like.

[0038] A polyester from a polyvalent alcohol and a polyvalent carboxylicacid is preferably used as the ester synthetic oil. Among these,polyester oils synthesized from a fatty acid and a polyvalent alcoholselected from pentaerithritol (PET), trimethylolpropane, (TMP), andneopentylglycol (NPG) are preferably used.

[0039] In the case in which hydrocarbon is used as the refrigerant,petroleum oils are preferably used as the refrigerating device oil whilein the case in which a flammable hydrocarbon fluoride is used as therefrigerant, ether synthetic oils such as polyvinylether are preferablyused as the refrigerating device oils. Further, a mixture of one or moretypes of refrigerating device oils may be used as the refrigeratingdevice oil.

[0040] Additives such as defoaming agents, antioxidants, moisture-and/oracid trapping agents, extreme pressure additives or antiabrasionimproving agents, and metal inactivating agents, especially copperinactivating agents, may be added to the refrigerating device oil. It ispreferable to use additives to prevent alterations (decomposition,oxidation, formation of sludge, and the like) of the refrigeratingdevice oil and alterations (corrosion) of the materials forming therefrigerating circuit. In addition, heat-resistance improving agents,corrosion preventing agents, rust-preventing agents and the like may besuitably added.

[0041] The additives to the refrigerating device oil do not only haveparticular effects on the refrigerating device oil itself, but alsoconsequently have certain effects on the sliding portions of thecompressor, the insulating materials, and the pipe metals. One or moretypes of these additives may be used. Further, as described above,because a mixture of the refrigerant and a small amount of refrigeratingdevice oil is circulated through the refrigerating circuit, therefrigerating device oil, to which the above additives are added, mustnot exert any harmful effects on the materials used in the refrigeratingcircuit.

[0042] As the defoaming agent, dimethylpolysiloxane oil,trifluoropropylmethyl silicone oil, phenylmethyl silicone oil and thelike are preferably used.

[0043] The added amount of the defoaming agent is preferably 1 to 50 wtppm with respect to the refrigerating device oil. When less than 1 wtppm is used, the effects of the defoaming agent are insufficient. Ifmore than 50 wt ppm is added, the effects as a defoaming agent do notincrease. Therefore, the aforementioned range is preferable.

[0044] By adding the defoaming agent, when the air within therefrigerant compressor and the circuit is removed before refrigerantsealing, the amount of foam generated from the refrigerating device oilis decreased, and entry of foam into the deaerating device can beprevented. In addition, foaming occurring at the time when the airdissolved in the refrigerating device oil is removed can be prevented.

[0045] The antioxidants may be hindered phenol antioxidants such asditertiary butylparacresol (DBPC), 2,6-di-t-butyl-4-methylphenol,4,4′-methylenebis (2,6-di-butylphenol),2,2′-thiobis(4-methyl-6-t-butylphenol) or the like; amine antioxidantssuch as P,P′-dioctyldiphenylamine, 3,7-dioctylphenothiazine,phenyl-α-naphthylamine, di(alkylphenyl)amine (wherein the alkyl grouphas from 4 to 20 carbon atoms), phenyl-α-naphthylamine,alkyldiphenylamine (wherein the alkyl group has from 4 to 20 carbonatoms), N-nitrosodiphenylamine, phenothiazine,N,N′-dinaphthyl-p-phenylenediamine, acridine, N-methylphenothiazine,N-ethylphenothiazine, dipyridylamine, diphenylamine, phenolamine,2,6-di-t-butyl-α-dimethylaminoparacresol and the like; and sulfurantioxidants such as alkyl disulfides or the like. Among these, DBPC isparticularly preferably used. The added amount of the antioxidant ispreferably 0.1 to 0.5 wt % with respect to the refrigerating device oil.When the amount is less than 0.1 wt %, the effects as an antioxidant areinsufficient. When an antioxidant is added in an amount exceeding 0.5 wt%, additional effects are not achieved. Thus, the aforementioned rangeis preferable.

[0046] The residual oxygen in the refrigerating circuit is preferably0.1 vol % or less with respect to the internal volume of therefrigerating circuit.

[0047] It is preferable to add a moisture- and/or acid trapping agent tothe refrigerating device oil. Water and acidic substances causecorrosion of the metals used in the compressor. In addition, water andacidic substances cause hydrolysis when an ester oil is used as therefrigerating device oil, and this frees the fatty acid components. Thisleads to the possibility of the refrigerating circuit being closed offdue to the generation of corrosion or metallic soaps, and of hydrolysisof the ester insulating materials.

[0048] Epoxy compounds, carbodiimide compounds, and the like may be usedas the moisture- and/or acid trapping agent. The epoxy compounds maytrap radicals. Examples of the epoxy compounds are glycidyl esters,glycidyl ethers, and the like. For example, a phenylglycidyl ether typeepoxy compound or an epoxydated fatty acid monoester or the like may beused. Phenylglycidyl ether or alkylphenylglycidyl ether, for example,may be used. The alkylphenylglycidyl ether has 1 to 3 alkyl groupshaving 1 to 13 carbon atoms. Examples of the epoxidated fatty acidmonoesters are esters of an epoxidated fatty acid having 12 to 20 carbonatoms, and an alcohol having 1 to 8 carbon atoms or a phenol oralkylphenol. In particular, esters of butyl, hexyl, benzyl, cyclohexyl,methoxyethyl, octyl, phenyl or the like of epoxystearic acid arepreferable. The added amount of the moisture- and/or acid-trapping agentis preferably 0.1 to 0.5 wt % with respect to the refrigerating deviceoil. When the amount is less than 0.1 wt %, the effect as a trappingagent is insufficient. When the amount is greater than 0.5 wt %,polymers tend to be generated. Thus, the above range is preferable. Itis preferable that the residual moisture is 500 wt ppm or less, and morepreferably 200 wt ppm or less, with respect to the total of therefrigerant and the refrigerating device oil. By using amoisture-trapping agent such as those mentioned above, the equilibriummoisture content within the refrigerating circuit, which content isexpressed by the following formula, can be kept to 200 wt ppm or less inthe initial stags of operation of the refrigerating device. When themoisture contents exceeds 500 wt ppm, icing tends to occur within thecapillary pipes. Further, hydrolysis, which is caused when a polyesteroil is used as the refrigerating device oil, and the generation of metalsoap sludge which accompanies such hydrolysis, can be suppressed.

[(residual moisture amount within refrigerating circuit)/(amount of oilfilled+amount of refrigerant filled)]×10⁶ wt ppm  Formula 1:

[0049] For example, a tertiary phosphate phosphorus compound which isthermally stable, such as triphenylphosphate (TPP) or tricresylphosphate(TCP), or the like may be used as the extreme pressure additive. Amongthese, TCP is particularly preferably used.

[0050] The added amount of the extreme pressure additive is preferably0.1 to 2 wt % with respect to the refrigerating device oil. If theamount is less than 0.1 wt %, the effects as an extreme pressureadditive are insufficient. If the added amount exceeds 2 wt %, noadditional effects are exhibited, and therefore, the above range ispreferable.

[0051] Examples of the metal (particularly, copper) inactivating agentare benzotriazole (BTA), triazole, triazole derivatives, thiadiazole,thiadiazole derivatives, dithiocarbamate, alizarin, qunizarin, and thelike. Among these, BTA is preferably used.

[0052] The added amount of the metal inactivating agent is preferably 1to 100 wt ppm with respect to the refrigerating device oil. If theamount is less than 1 wt ppm, the effects as a metal inactivating agentare insufficient. If the added amount exceeds 100 wt ppm, no additionaleffects are obtained. Therefore, the above range is preferable.

[0053] The drying agent is preferably a synthetic zeolite or the like.Among synthetic zeolites, sodium A type synthetic zeolite and potassiumA type synthetic zeolite are preferable. Further, in order for thezeolite particles to effectively trap the moisture within therefrigerating circuit, it is preferable for the effective diameterthereof to fall in the range of 3 to 6 Å.

[0054] The drying device used in the refrigerating device may be one inwhich the drying agent is accommodated within a container, and thecontainer is connected by a pipe to the refrigerating circuit.

[0055] Hereinafter, the present invention will be described specificallyby an Example. However, it is to be noted that the present invention isnot limited to this example.

EXAMPLE 1

[0056] A refrigerating device was assembled by using materials such asthe following, by using the refrigerating circuit shown in FIG. 1.

[0057] refrigerant: isobutane (purity 99.7 vol %, 0.001 wt % ofunsaturated hydrocarbon, 0.05 wt ppm of sulfur)

[0058] odorant: tetrahydrothiophene (0.1 wt % with respect to therefrigerant)

[0059] refrigerating device oil: paraffin oil

[0060] viscosity (40° C.):15 cSt

[0061] volume specific resistivity: 10¹⁵ Ω·cm

[0062] refrigerating device oil aditives (added amount is wt % withrespect to refrigerating device oil)

[0063] defoaming agent: silicone defoaming agent (10 ppm)

[0064] antioxidant: DBPC (0.3%)

[0065] moisture- and/or acid-trapping agent: epoxy compound (0.25%)

[0066] extreme pressure additive: TCP (1%)

[0067] copper inactivating agent: BTA (5 ppm)

[0068] drying agent: synthetic zeolite (effective diameter: 3 Å)

[0069] The above refrigerant had a unique smell (a smell like that ofcoal gas), and it was easy to detect the leakage of the refrigerant evenin a small amount. Further, after operation of the above refrigeratingdevice for 2000 hours, the state of the inner surface of the copper pipeof the refrigerating circuit and the inner surface of the capillary tubewere inspected, and were found to have no corrosion.

[0070] As described above, in the refrigerant of the present invention,by using tetrahydrothiophene as the odorant and due to its smell, it iseasy to detect the leakage of the refrigerant from the refrigeratingdevice. In addition, the odorant has good reactivity with therefrigerant and the refrigerating device oil. In particular, therefrigerant does not react with copper forming the refrigeratingcircuit, and causes no corrosion at the surface of the copper. Further,the refrigerant has no reactivity with the refrigerating device oil.Therefore, clogging of the refrigerating circuit due to insolublereaction products will not occur even after operation for a long periodof time.

What is claimed is:
 1. A refrigerant comprising: (i) a hydrocarbonhaving 1 to 4 carbon atoms, or a flammable hydrocarbon fluoride derivedby substituting one or more hydrogen atoms of the hydrocarbon withfluorine atoms, as a main component, and (ii) a tetrahydrothiophene asan odorant.
 2. The refrigerant of claim 1 wherein the amount of theodorant is in the range of 10 wt ppm to 0.5 wt %.
 3. The refrigerant ofclaim 1, wherein purity of the hydrocarbon or the flammable hydrocarbonfluoride is at least 99.0 vol %, the content of unsaturated hydrocarbonis no more than 0.01 wt %, and the entire sulfur content is no more than0.1 wt ppm.
 4. The refrigerant of claim 2, wherein purity of thehydrocarbon or the flammable hydrocarbon fluoride is at least 99.0 vol%, the content of unsaturated hydrocarbon is no more than 0.01 wt %, andthe entire sulfur content is no more than 0.1 wt ppm.
 5. A refrigeratingdevice comprising: (a) a compressor, a heat releasing device, anexpansion mechanism, and an evaporator connected to form a refrigerationcircuit, and (b) a refrigerant disposed in the refrigeration circuit,wherein the refrigerant comprising: (i) a hydrocarbon having 1 to 4carbon atoms, or a flammable hydrocarbon fluoride derived bysubstituting one or more hydrogen atoms of the hydrocarbon with fluorineatoms, as a main component, and (ii) a tetrahydrothiophene as anodorant.
 6. The refrigerating device of claim 5, wherein a refrigeratingdevice oil used in the compressor has a viscosity at 40° C. of 5 to 300cSt.
 7. The refrigerating device of claim 5, wherein the refrigeratingdevice oil includes a metal inactivating agent.
 8. The refrigeratingdevice of claim 6, wherein the refrigerating device oil includes a metalinactivating agent.
 9. The refrigerating device of claim 5, wherein therefrigerating device oil includes one or more additives selected fromthe group consisting of moisture- and/or acid trapping agents,antioxidants, and extreme pressure additives.
 10. The refrigeratingdevice of claim 6, wherein the refrigerating device oil includes one ormore additives selected from the group consisting of moisture- and/oracid trapping agents, antioxidants, and extreme pressure additives. 11.The refrigerating device of claim 8, wherein the refrigerating deviceoil includes one or more additives selected from the group consisting ofmoisture- and/or acid trapping agents, antioxidants, and extremepressure additives.
 12. The refrigerating device of claim 5, whereinresidual oxygen in the refrigerating circuit is no more than 0.1 vol %of an internal capacity of the refrigerating circuit, and a residualmoisture content in the refrigerating circuit is no more than 500 wt ppmwith respect to a total of the refrigerant and the refrigerating deviceoil.
 13. The refrigerating device of claim 6, wherein residual oxygen inthe refrigerating circuit is no more than 0.1 vol % of an internalcapacity of the refrigerating circuit, and a residual moisture contentin the refrigerating circuit is no more than 500 wt ppm with respect toa total of the refrigerant and the refrigerating device oil.
 14. Therefrigerating device of claim 8, wherein residual oxygen in therefrigerating circuit is no more than 0.1 vol % of an internal capacityof the refrigerating circuit, and a residual moisture content in therefrigerating circuit is no more than 500 wt ppm with respect to a totalof the refrigerant and the refrigerating device oil.
 15. Therefrigerating device of claim 5, wherein the refrigerating circuit ismade of copper or copper alloy.
 16. The refrigerating device of claim 5,wherein the refrigerating circuit further includes a drying device. 17.The refrigerating device of claim 6, wherein the refrigerating circuitfurther includes a drying device.
 18. The refrigerating device of claim8, wherein the refrigerating circuit further includes a drying device.19. The refrigerating device of claim 16, wherein the drying devicecontains a synthetic zeolite whose effective diameter falls in the rangeof 3 to 6 Å.
 20. The refrigerating device of claim 18, wherein thedrying device contains a synthetic zeolite whose effective diameterfalls in the range of 3 to 6 Å.